Diesel engine



FIG. 1 is a front view of a diesel engine according to the present application, showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a first perspective view thereof; and,

FIG. 8 is a second perspective view thereof.

The elements of the diesel engine encircled by broken lines form no part of the claimed design. 

CLAIM The ornamental design for a diesel engine, as shown and described. 